Safety track switch control system



Dec. 17, 1957 R. F. WELLS SAFETY TRACK SWITCH CONTROL SYSTEM Filed Nov.18, 1954 4 Sheets-Sheet l FIGQIA INVENTOR. R.F.WELLS HIS ATTORNEY Dec.17, 1957 R. F. WELLS SAFETY TRACK SWITCH CONTROL SYSTEM Filed Nov. 18,1954 4 Sheets-Sheet 2 FIG. 18.

3A 3B 5 66- 5T 2-7T D Mi N A S n W w W 6 3 T v m a B EW 6 A R mT T FR BOE Hm E S mm LP INVENTOR. RFWELLS HIS ATTORNEY United States Patent Ofi2,837,913 Patented Dec. 17, 1957 ice SAFETY TRACK SWITCH CONTROL SYSTEMRobert F. Wells, Rochester, N. Y., assignor to General Railway SignalCompany, Rochester, N.

Application November 18, 1954, Serial No. 469,752

6 Claims. 01. 246-161) This invention relates to safety track switchcontrol systems for railroads, and it more particularly pertains to theautomatic control of a railway track switch in accordance with the speedand/ or class of an approaching train.

When a railway grade is such as to be dangerous in case the brakes of atrain proceeding down the grade should fail to keep the train undercontrol, a derail or safety track is often provided having sand on thetrackway in which a train with insuflicient brake control may be broughtto a stop with a minimum amount of damage. General practice is that aswitchman is required at the safety track to operate a track switchconnecting the safety track to the main track in accordance with whetheror not an approaching train is under safe braking control. The normalposition of such a track switch is in alignment for traflic into thesafety track.

The system according to the present invention eliminates the need of aswitchman stationed at the safety track, and provides automatic meansfor governing the safety track switch in accordance with the speed of anapproaching train. It is further provided that by the use of trackcircuits in approach of the safety switch, it can be determined as toWhether the approaching train is a passenger or a freight train. If itis a freight train that is approaching the safety track, the safetytrack switch is reversed only if the speed of the train is below a givenlimit as determined by a timer. If it is a passenger train that isapproaching the safety track, the safety track switch is reversed onlyif the speed of the train is below a higher given speed limit asdetermined by another timer. The safety switch is automatically operatedback to its normal position after passage of a train upgrade, eventhough there has been no action taken on the part of the operator of acentralized traffic control machine providing supervisory control of thetrack switch. This is to provide derail protection in case the rear endof the train proceeding upgrade should become uncoupled and out ofcontrol.

An object of the present invention is to automatically operate a trackswitch in accordance with the speed of an approaching train.

Another object of the present invention is to automatically detect theclass of a train and to select a timer for operation in accordance withthe class of train detected.

Another object of the present invention is to automatically operate atrack switch in accordance with the speed and class of an approachingtrain.

Another object of the present invention is to operate a track switch inaccordance with the completion of operation of one of a plurality oftimers selected in accordance with the class of an approaching train.

Another object of the present invention is to detect by track circuitsthe class of a train approaching a track switch, detect the speed rangeof the train and operate the track switch in accordance with whether ornot the speed of the train exceeds a predetermined maximum speed for theparticular class of train detected.

Other objects, purposes and characteristic features of the presentinvention will be in part obvious from the accompanying drawings and inpart pointed out as the description of the invention progresses.

In describing the invention in detail, reference is made to theaccompanying drawings in which similar reference characters are used todesignate corresponding parts and in which:

Figs. 1A and 1B when placed side by side illustrate one embodiment ofthe present invention as applied to the control of a safety track switchbetween two passing sidings;

Figs. 2A to 26 are track diagrams illustrating diiferent stages in theprogress of an eastbound train; and

Figs. 3A to 36 are diagrams illustrating the sequence of operation ofrelays and control devices for traffic conditions as illustrated in therespective diagrams of Figs. 2A to 2G.

Conventional schematic diagrams have been used for disclosure of thesystem organization in the drawings, the drawings being prepared moreparticularly to facilitate an understanding of the mode of operation andthe principles involved, rather than to show the details in constructionand the specific arrangement of components that may be provided by thoseskilled in the art in accordance with the requirements of practice. Thesymbols and have been used to indicate connections to the respectivepositive and negative terminals of suitable batteries or other sourcesof direct current, and the symbols (B+) and (B) have been used toindicate connections to the respective positive and negative terminalsof a split battery having a center tap (CN) The track layout for oneembodiment of the present invention is illustrated in Fig. 1B as being astretch of single track 10 having traflic in both directions. It isassumed that traffic to the right is down grade and eastbound trafiic.Passing sidings A and B are associated with the stretch of main track 10and are spaced by a block including track sections 2T, 5T, 2-7T, A4T,B4T and 3T. Adjoining the track section 3T at the east end is a tracksection 6T. These track sections are used in the conventional manner forthe control of the signals, and in addition the track sections A4T andB4T are used to govern the operation of timers associated with theoperation of a track switch 3W. The track section A4T is used todetermine by its length as to whether short or long trains, generallypassenger or freight trains respectively, are approaching the trackswitch 3W. Thus, the track section A4T is made of a length such that thelongest passenger train to be expected can just be in cluded within thelimits of the track section. A track relay TR is provided for each ofthe track sections and is controlled by a conventional track circuit(not shown). Thus, track relays 2-7TR, A4TR, B4TR, 3TR and 6TR areprovided for the associated track sections 27T, A4T, B4T, ST and 6Trespectively. Passing siding A is connected at its right hand end to themain track 10 by the track switch 2W, and passing siding B is connectedat its left hand end to the main track 10 by a track switch 4W.

A sand track is provided for stopping trains which cannot be controlledin going down the grade, and this track is connected normally to themain stretch of track 10 by a track switch 3W at a point just west ofthe west end of the passing siding B. The sand track is constructed withsand on the trackway so as to stop any train with the minimum amount ofdamage. It is to be understood that other means for stopping trains onthis track could be used in accordance with the requirements ofpractice, such, for example, as car retarders, derails and the like. Thetrack switches are power operated by conventional power switch machinesSM, the switch machine 35M being provided for the power operation oftrack switch 3W.

Signals of any suitable type are provided for governing traflic in bothdirections through the main stretch of track and into the passingsidings. The signals illustrated are assumed to be of the searchlighttype, signals 2A, 2B, 4, 6A and 6B being provided for governingeastbound traffic and signals 7A, 7B, 5, 3A and 3B being provided forgoverning westbound traffic.

It is assumed that the signals at the ends of the passing sidings arecontrolled by a suitable centralized traffic con trol system such, forexample, as the code communication system disclosed in the patent to W.D. Hailes et al., No. 2,399,734, granted May 7, 1946. Respective switchand signal control relays 3WZ, 6RGZ and 7LGZ'are assumed to be subjectto control by the operator of a centralized trafiic control system suchas that of the Hailes et al. patent, for example, but for simplicity,the relay 3WZ is illustrated as being energized directly from a switchcontrol lever SML that is assumed'to be provided on the centralizedtrafiic control machine. The relay 3WZ is of the magnetic-stick type anditis provided for governing the operation of track switch 3W. Relays6RGZ and 7LGZ are provided for governing signals 6 and 7.

Timing devices PTE, FTE and TE are provided in association with arepeater relay TEP for the purpose of determining when the speed of anapproaching train is such that the train is under control and mayproceed safely down the grade over the track switch 3W in its reverseposition. These timing'devices can be of the .type disclosed, forexample, in the patent to O. 8. Field, No. 2,378,293 granted June 12,1945.

Stick relays 7ASPS, BPS and BTS are providedfor the control of relayTEP, particularly for governingithe operation of the track switch SW forwestbound traflic and switching operations.

Lock relays 3L and 3LSare provided for insuring safe operation of thetrack switch SW, and a:relay 3WPP is provided to restore track switch 3Wto its former position in case of an obstruction which prevents fulloperation of the track switch 3W. The operation .of the track switch 3Wis normally governed by a relay SWPP.

Switch repeater relays 3NWP and 3RWP are provided for repeating therespective normal and reverse locked positions of the track switch 3W,these relays are controlled according to conventional practice by asuitable switch circuit controller that is-assumed to be included in theswitch machine M.

Relays 7H and 4H are relays used for the control of signals 7 and 4respectively in accordance with the condition of occupancy of thetrackway in advance of the associated signals.

Time locking relays 6A8 and 7A5 are for providing a predetermined timedelay before a track switch can be operated after signal 6 or-signal 7has been ut to stop. These relays have thermal time element devices 6THand 7TH respectively associated therewith. Relays 6RP and 7RP areprovided for repeating the stop positions of the mechanisms of signals 6and 7 respectively.

Having thus considered the organization of the apparatus in general, amore detailed consideration will be given to the circuit organizationupon consideration of typical operating conditions of the system.

Operation The normal conditions of the system are assumed to be thoseconditions where there are no trains present inthe track layout, thesignals subject to centralized traffic control are at stop incorrespondence with their associated levers on the centralized 'tralficcontrol machine (not shown), and the track switches are in their normalpositions in correspondence with associated levers SML on the controlmachine. In accordance with there being no trains present, the trackrelays TR are in their energized positions, and in accordance with thesignals being at stop, the associated stop repeater relays, such as therelays 6RP and 7RP for the signals 6 and 7 respectively are in theirenergized positions. The relays 6A5 and 7A5 which are associated withsignals 6 and 7 respectively are normally maintained in their picked uppositions by the energization of their stick circuits. Thus relay 6AS isnormally energized by a circuit extending from including front contact11 of relay 6RP, front contact 12 of relay 3TR, winding of thermal relay6TH, front contact 13 of relay 6A8 and winding of relay GAS, to Theresistance of the winding of relay 6AS is such as to prevent theoperation of the thermal relay 6TH because of there being insufficientcurrent passing through the winding of that relay to cause anyappreciable heating eifect. Similarly, the relay 7AS is normally held upby a stick circuit extending from including front contact 14 of relay7RP, front contact 15 of relay 3TR, winding of thermal relay 7TH, frontcontact 1.6 of relay 7A5 and winding of relay 7A5, to

Inasmuch as the signal 4 is an automatic signal, the home relay 4H forgoverning that signal is normally energized by a circuit extending fromincluding front contact 17 of relay B4TR (see Fig. 1A), front contact 18of relay A4TR, wire 19, back contact 20 of timer PTE, back contact 21 oftimer PTE, back contact 22 of timer TE, back contact 23 of relay TEP,front contact 24 of relay 3TR, front contact 25 of relay 3NWP, frontcontact 26 of relay 7AS, front contact 27 of relay 3WPP, and winding ofrelay 4H, to This relay when picked up checks that the timers areproperly restored and energizes signal 4 through its front contact 28 tocause signal 4 to display a caution indication. Signal 4 is a twoposition signal operable to display yellow or red aspects when thesignal mechanism is energized or deenergized respectively.

The lock relay 3L is normally energized by a circuit extending fromincluding back contact 29 of relay 7LGZ, back contact 30 of'relay 6RGZ,front contact 31 of relay 3TR, front contact 32 ofrelay 6A8, frontcontact 33 of relay 7A8 and winding of relay 3L, to Relay 3LS is alsonormally energized by its pick up circuit which is closed at frontcontact 34 of relay 3L. A stick circuit is provided for relay 3LS whichis closed, when the switch machine 3SM is in midstroke, through backcontact 35 of relay 3NWP, back contact 36 of relay SRWP, and frontcontact 37 of relay 31.5.

The relay 7H, which is provided for the control of the clearing ofsignal 7 does not have its control/circuit illustrated, but it is to beunderstood that this relay is energized in accordance with the entireblock between the passing sidings A and B being unoccupied by awestbound train and in accordance with there being no signal clearingcontrol set up from the control ofiice for the clearing of the opposingsignal 2. The circuit for the control of relay 7H can be provided, forexample, as is fully disclosed for the control of relay 71-1 in thepatent to S. N. Wight No. 2,082,436, granted June 1, 1937.

The stick relay 7ASPS is normally energized by a circuit extending fromincluding front contact 38 of relay 7AS, front contact 39 of relay 3TR,wire 40, front contact 41 of relay 2-7TR, front contact 42 of relayA4TR, front contact 43 of relay B4TR, and winding of relay 7ASPS, to Astick circuit is also normally closed for this relay including frontcontact 38 0f relay 7AS, wire 44, and front contact 45 of relay 7ASPS.

The switch circuit pole changing relay 3WPP is normally energizedthrough back contact 46 of relay SWRP.

To consider the mode of operation of the system upon passage of a traindowngrade, it will be assumed that an eastbound train is approachingsignal 2A. As has been heretofore pointed out, the clearing of thesignal 2A causes the dropping away of relay 7H, and thus relay 7H isdropped away upon the transmission of a control from the control ofiicefor clearing signal 2A.

Upon the approach. of the train, the operator of the centralizedtrafi'ic control machine controls the track switch 4W to a position inaccordance with whether or not it is desired that the train shall enterthe passing siding B, and the signal control lever associated withsignal 6 is actuated to a signal clearing position. The operator of thecontrol machine also operates the lever SML (see Fig. 1B) for actuationof the magnetic stick relay 3WZ to its dropped away position for thereversal of the track switch 3W. The controls designated by the operatorof the control machine are sent out to the field, and in accordancetherewith the relay 6RGZ is picked up, and the relay 3WZ is driven toits dropped away position. The lock relay 3L which is associated withtrack switch 3W is not dropped away upon the picking up of relay 6RGZfor clearing signal 6 because of energy being supplied to relay 3Lthrough front contact 61 of relay 3NWP. Thus relay 3L is maintainedpicked up until the operation of track switch 3W is initiated.

It will now be assumed that the eastbound train enters the block betweenthe passing sidings A and B and proceeds to a point to cause thedropping away of the track relay 2-7TR. The dropping away of this relaycauses the picking up of relay BPS by the energization of a circuitextending from including back contact 47 of relay 2-7TR, front contact48 of relay A4TR, front contact 49 of relay B4TR, front contact 50 ofrelay 7ASPS, and winding of relay BPS, to Upon the picking up of thisrelay, a stick circuit is closed through front contact 51 of relay BPSshunting contacts 48, 49 and 50 out of the circuit just described.Energy may also be applied to this stick circuit upon the closure ofback contact 48 of relay A4TR and upon the closure of back contact 52 ofrelay B4TR.

As the train progresses further so as to enter the track section A4T,upon accepting the caution indication of the automatic signal 4, thetimers PTE and FTE become initiated simultaneously. These timers becomeenergized at this time through back contact 53 of relay 3WZ, wire 54,front contact 55 of relay BPS, front contact 56 of relay 7ASPS, frontcontact 57 of relay B4TR, back contact 58 of relay A4TR, wire 59, andback contact 60 of relay TEP.

The timers PTE and FTE have their times of operation set for the minimumtimes respective passenger and freight trains may consume in the frontends of the trains passing from the point of entrance to the tracksection A4T to the point of entrance to the track section B4T, and yetbe under safe speed control. For a typical condition, this time may becomparable to a speed of 22 miles per hour for passenger trains and aspeed of 8 miles per hour for freight trains. Thus, it will be seen thatin view of the fact that both timers PTE and FTE are initiated at thesame time, the timer PTE will complete its operation a substantial timebefore the. completion of operation of the timer FTE.

If the passage of a passenger train is considered, when the train isadvanced to a point as illustrated in the diagram of Fig. 2D, the trackrelay 2-7TR becomes picked up before the track relay B4TR has beendropped away. If at this time the timer PTE has completed its operation,the system follows a sequence of relay operations as is illustrated bythe sequence chart of Fig. 3D. This sequence of operations followsirrespective of whether or not the timer FTE has had time to completeits operation.

Upon completion of operation of the timer PTE, the relay TEP becomespicked up by the energization of a circuit extending from including backcontact 53 of relay 3WZ, wire 54, front contact 55 of relay BPS, frontcontact 56 of relay 7ASPS, front contact 57 of relay B4TR, back contact58 of relay A4TR, front contact 62 of relay 27TR, wire 63, front contact64 of relay PTE, and winding of relay TEP, to 'lh is relay when pickedup is maintained energized by a stick 'circuitextending from includingback contact 53 of relay 3WZ, wire 54, front contact 55 of relay BPS,front contact 56 of relay 7ASPS, wire 65, front contact 66 of relay TEPand winding of relay TEP, to It will be noted that in order that therelay TEP may be picked up by the circuit that has been described, thefront contact 62 of relay 2-7TR must be closed. It is this circuitselection that determines that the train approaching is short enough tobe entirely contained within the track section A4T, and thus should besafely under control if proceeding at a rate up to 22 miles per hour.

The picking up of relay TEP causes the picking up of the relay 3WRP forapplication of energy to the switch machine 38M. Relay 3WRP is energizedby a circuit extending from including back contact 53 of relay 3WZ,front contact 67 of relay TEP and winding of relay 2WRP, to This relaywhen picked up connects the positive terminal of a suitable source ofdirect current to the control wire 68 for the switch machine 3SM throughback contact 69 of relay 3WZ, front contact 70 of relay 3WPP, frontcontact 71 of relay 3WRP, and front contact 72 of relay 3LS. Thenegative terminal of the source of direct current for operation of theswitch machine is connected to the control wire 73 for switch machine3SM through back contact 74 of relay 3WZ, front contact 75 of relay3WPP, front contact 76 of relay SWRP, and front contact 77 of relay 3LS.

The circuit by which the relay 3L has been energized through frontcontact 61 of relay SNWP is opened when the switch machine 3SM startsits operation, and thus the relay 3L is dropped away because it isassumed that the relay 6RGZ has been picked up for the clearing ofsignal 6' and thus the back contact 30 of. relay 6RGZ in the circuit forrelay 3L is open at this time. The dropping away of relay 3L, however,does not immediately cause .the release of relay 3LS upon the opening offront contact 34 of relay 3L because the relay 3LS is held by its stickcircuit when the switch 3W is in mid stroke. This stick circuit isclosed from including back contact 35 of relay 3NWP, back contact 36 ofrelay SRWP, front contact 37' of relay 3L5, and winding of relay 3LS, to

Upon completion of the operation of the track switch 3W to its reverseposition, the reverse switch repeater relay 3RWP becomes picked up andrelay 3LS is dropped away. Relay 3LS shunts the control wires 68 and 73for switch machine 3SM through back contacts 72 and 77.

A circuit is then closed for clearing signal 6A or 6B as selected inaccordance with the position to which the track switch 4W has beenoperated. The energization of either of these mechanisms 6A or 6B isthrough front contact 78 of relay 6RGZ, front contact 79 of relay 3RWP,and such other selections as are generally required as indicated by xxxand by the dotted line extending to the signal mechanism 6A and 6B. I

The slow release relay SWPP is deenergized upon the picking up of theswitch control relay SWRP for initiating operation of the track switch3W, but if there is no obstruction to complete operation of the trackswitch,

the track switch 3W completes its operation to its reverse position andpicks up relay 3RWP in time to maintain relay 3WPP picked up by applyingenergization through front contact 80 of relay 3RWP. If the track switch3W should be obstructed, the relay 3RWP would not be picked up, and thusthe relay 3WPP would become dropped away. In other words, the relay 3WPPis made sufficiently slow in dropping away to hold over for the ordinaryoperating time of the track switch 3W so that this relay is dropped awayon switch operation only provided the track switch 3W fails to completeits operation.

The dropping away of relay 3WPP when the track switch. 3W is inmid-stroke pole changes the control wires 73 and 68 by the shift ng of cn a ts 70 and' S, a

hus est s he. pera io f t e t ac s it h W1to i f rmer p siti nt len t ofa tr i is. s h tha th a k ec o B4T-must be entered before the tracksection '2-7T is a te th m r pea e e y TE ca notibe Pic p p n compl i ot per tion f he timer-PI as ha be n desc ibed becau e th pick-up circuifor r lay E i udin the time YEH requires the-closur 015 fr nt onta 6. ofe ay -3 .l the l sur of ont contac 7 o r ay B4 R- i t e rain s o g i sne essary t a h speed of t e train e c nid a y less a o a short t ain.so hat t e timer hich h s a l n time et ing hanth t me FIE has me tcomplet i operat on befo e e t of th trac s ct nn 134T. When he i erFTEcPl te t ope a io wi t ac r ay 2- i i deenersiz t p s i n and thetra kre1ayB4TR pi k up a ci c t is l sed for t e pick n up of relay T P vtending from including back contact 53 of relay 3 Z W r front n act 55 freI Y PS, f ont contact 56 of relay 7ASPS, front contact 57 of relay,B4TR, back contact 58 of relay A4TR, back contact 62 ofrelay R., wire1, front on ac 82 of relay FTE, a wind ng o l y E to The p k g up f r yTEP under these conditions establish s astick circuit for relay TEP thathas been described for maintaining, this relay picked up irrespective ofthe condition of occupancy of the respective track sections 2-7T, A4Tand B4T.

Upon the picking up of relay TEP as has been described in accordancewith the completion of operation of the timer FTE, the track switch 3Wis operated to its reverse position and the signal 6 is cleared in thesame manner that has been described when it was assumed that the relayTEP was picked up by the completion of operation of the timer PTE.

It is further provided that if a train occupies the track section B4Tfor a predetermined length of time as measured by the timer TE, therelay TEP can be picked up and the track switch 3W can be operated toits reverse position. This timer is used particularly for switchingmoves, but it can also be effective for the normal progress of aneastbound train (as is illustrated in the diagram of Fig. 2G) if thetrain should not reduce its speed sufficiently within the track sectionA4T to have permitted either the timer PTE or the timer FTE to completeits operation, but should reduce its speed materially in the tracksection B4T before entering the detector track section 3T.

The circuit by which the timer TE is energized upon the dropping away ofthe track relay B4TR extends from (l) including back contact 53 of relay3WZ, Wire 54, front contact 55 of relay BPS, front contact 56 of relay7ASPS, back contact 57 of relay B4TR, Wire 83, back contact 84 of relayTEP, front contact 85 of relay STR and winding of relay TE, to Upon thepicking up of relay TEP, the relay 3WRP is picked up by the energizationof a circuit that has been described, and the picking up of this relaycauses the power operation of the track switch 3W to its reverseposition in the same manner as has been specifically described whenconsider-' ing the picking up of relay TEP in accordance with thecompletion of operation of the timer PTE.

To consider restoration to normal conditions of the apparatus afterpassage of an eastbound train, it will be -energiz ed according to theusual practicein centralized traflic control systems, but the closureofits back contact 30 in the circuit for the lock relay 3L cannot causethe picking up of this relay-because the circuit for relay 3L is open atthis time at front contact'31 of relaySTR. The stick relay 6A5 becomesrestored 'to its normally energized condition after the train hasentered track sectionoT. The circuit by which the relay 6A5 is picked upextendsfrom (+),inc1u ding front'contact 11 of relay 6RP, back-contact12 of relay 3TR, back contact'86 of relay 6TR;andiwinding of relay 6AS,to

'When the eastbound train leaves the track section B4T, the picking upof relay 'B4TR removes energy from relay BPS at back contact 52 andcauses the relay BPS to be restored to its normally, deenergizedposition. The dropping away of relay BPS removes energy from relay TEPby the opening of front contact; 55 because relay BTS is in its deenergized position at this time as this relay is picked up only for aswitching move for westbound traflic.

Relay TEP in dropping away causes the dropping away of relay SWRP byopening it circuit at front contact 67, the front contact 87 of relay 7Hwhich is connected in multiple with front contact 67 of relay TEP beingopen at this time because of the presence of the train in the blockbetween passing sidings A and B. The dropping away of relay SWRP polechanges the control wires 73 and 68 except that energy cannot be appliedto these control wires until the picking up of the lock stick relay 3LSto close front contacts 72 'a nd'77 in the circuit for the control ofthe switch machine 35M. Relay 3L5 cannot'be picked up untilthepicking upof the lock relay 3L which in turn cannot be picked up until the tracksection 3T becomes unoccupiedin the rear of the train so as to closefront ,contactfilofrelaylsTR.

When'the track section'ST becomes unoccupied in the rear of theeastbound train, the relay 7H is picked up, provided-there isno'following train in the block between the passing sidings A and B; Thepicking up of relay 7H causes the picking up of relay SWRP upon theclosure of its front contact 87, assuming that the back contact 53 ofrelay SWZ is still closed. Also, when the track section 3T becomesunoccupied ,in the rear of the train, the closureof'front contact 31' ofrelay '3TR in the circuit for the lock relay 3L causes the picking up ofthat relay, which in turn, by the closure of its front contact 34,causes the picking up of the relay 3L8 to apply energy to the switchmachine 33M of a polarity to maintain that switch machine in its reverseposition until the operator at the control ofiice operates his lever SMLback to its normal position. When this is done, the picking up of relay3WZ reverses the polarity of energization of the switch machine 33M tocause the operation of the track switch 3W to its normal position. Underthese conditions the control wires 68 and 73 for the switch machineSSMare energized through circuit selections that have been described whenconsidering the normal conditions of the system.

For the particular embodiment of the present invention underconsideration, the distance between the passing sidings A and B is suchthat it is not proposed to clear the signal 2A or the signal 213 for afollowing eastbound train movement until the first train has left thedetector track section 3T. In order for the operator of the controlmachine to clear a signal 2A or 2B for a following train, it isnecessary that he first operate his lever SML to its normal position forthe operation of the track switch 3W to its normal position. When theswitch 3W has b en, operated to its normalposition, an indication of itsposition is transmitted to the control ofiice. This indication ofthenormal position of the track switch 3W switch 3W to its reverse positionin setting up a route for a westbound train is such that no timing isrequired,

provided that the block between the passing sidings A and B is clear ofeastbound trains and that the signals 2A and 2B are at stop as isindicated by the energized condition of the relay 7H. With the relay 7Hpicked up, the closure of front contact 87 provides that the relay SWRPis energized whenever the operator at the control ofiice operates hislever SML to its reverse position as as to drive the magnetic stickrelay 3WZ to its dropped away position. As has been pointed out, thepicking up of relay 3WRP pole changes the control Wires 68 and 73 toenergize the switch machine 3SM with a polarity for operation of thetrack switch 3W to its reverse'position.

It is desirable for safety purposes that the track switch 3W be restoredto its normal position in the rear of a westbound train as soon as thattrain has passed out of the detector track section 3T. This gives derailprotection in the rear of the train in case part of the train shouldbecome uncoupled and roll uncontrolled down the grade. Operation of thetrack switch 3W to its normal position under these conditions isaccomplished be cause the relay 7H is in its dropped away position atthat time and thus the relay 3WRP has been dropped away to pole changethe control wires 68 and 73 for the switch machine 38M. Even though theback contacts 74 and 69 of relay 3WZ are closed because the operator ofthe control machine has not yet restored his switch lever SML to itsnormal position, the switch machine 3SM becomes energized with properpolarity tooperate the track switch 3W to its normal position upon thepicking up of relay 3LS when the track section 3T becomes unoccupied inthe rear of the westbound train. Under these conditions energy isapplied to the switch machine control wire 73 from the positive terminalof a suitable source of energy through back contact 69 of relay 3WZ,front contact 70 of relay SWPP, back contact 88 of relay 3WRP, and frontcontact 77 of relay 3LS. The negative terminal of this source of energyis connected to the switch machine control wire 68 through back contact74 of relay 3WZ, front contact 75 of relay 3WPP, back contact 89 ofrelay SWRP and from contact 72 of relay 3LS. 5 There will be anindication transmitted to the control oflice that the track switch 3Whas been operated to its normal position, and the reception of theindication at the control oflice that the track switch 3W has beenoperated to its normal position sets up an out-ofcorrespondenceindication that informs the operator of the control machine that heshould operate his switch control lever SML to its normal position incorrespondence with the position to which the track switch 3W has beenoperated. This operation provides for the picking up of the magneticstick relay 3WZ which completes the restoration to normal conditions ofthe organization for energization of the switch machine 3SM.

The timers PTE, FTE and TE are not operated for normal westbound trafiicbecause the normally energized relay 7ASPS is dropped away upon theclearing of a signal 7A or 7B for governing westbound traffic. This isaccomplished by the opening of front contact 38 of relay 7AS upon theclearing of signal 7A or 7B. Although relay 7AS is restored when thewestbound train enters the track section B4T, relay 7ASPS cannot pick upbecause its pick-up circuit includes front contacts 41, 4-2 and 43 ofrelays 27TR, A4TR and B4TR re spectively in series. The circuit by whichthe relay 7AS is picked up when a westbound train enters the tracksection B4T extends from including front contact 14 of relay 7RP, backcontact 15 of relay 3TR,

wire 90, back contact 91 of relay B4TR, wire 92, and

'winding of relay 7AS, to Thus, the relay 7ASPS remains in its droppedaway position as the westbound train progresses, and the opening of itsfront contact "56 prevents energization of the timers.

Provision has been made for switching moves at the left-hand end of thepassing siding B, and one condition under which switching is desirableat this location is where a long train coming up grade is required todivide and leave part of the train on the passing siding B because ofbeing unable to take such a long train up the steep grade ahead.

A train to divide under these conditions proceeds with its front endextending into the block between the passing sidings A and B and leavesthe rear portion of the train in the track section GT and proceeds to aclearance point behind the signals 6A and 6B for a switching operationinto the passing siding B. As soon as the track section 3T becomesunoccupied in the rear of the train as it proceeds into the tracksection B4T, the track switch 3W is restored automatically to its normalposition as has been described. To'reverse the track switch 3W andpermit the train to back into the passing siding B it is necessary towait for the timer TE to operate.

As a means of permitting the operation of the timer TE for causingreverse operation of the track switch 3W for a switchingmovement, it isprovided that the relay BTS is picked up when a route is called for fora westbound train by the clearing of signal 7A or signal 7B. The pick-upcircuit for relay BTS extends from including front contact 93 of relay7H, front contact 94 of relay 3TR, front contact 95 of relay 7LGZ, wire96, and winding of relay BTS, to This relay is maintained picked up aslong as the track section 6T is occupied by a stick circuit extendingfrom including back contact 97 of relay 6TR, wire 98, front contact 99of relay BTS, and winding of relay BTS, to With relay BTS picked up,track section B4T occupied, and track section 3T unoccupied, adistinctive condition is indicated wherein a switching move is calledfor in that the train has been divided, part of the train beeing left inthe track section 6T, and the first part of the train being in positionfor a switching operation into the passing siding B.

Thus, tthe timer TE becomes energized when the track relay 3TR is pickedup to close front contact 85, the circuit for the energization of therelay TE extending from including back contact 53 of relay 3WZ, wire 54,front contact 100 of relay BTS, back contact 101 of relay B4TR, backcontact 57 of relay B4TR, wire 83, back contact 84 of relay TEP, frontcontact 85 of relay 3TR, and winding of relay TE, to After the timer TEhas completed its operation, the relay TEP becomes picked up by theenergization of a circuit extending from including back contact 53 ofrelay 3WZ, wire 54, front contact 100 of relay BTS, back contact 101 ofrelay B4TR, back contact 57 of relay B4TR, wire 83, front contact 102 ofrelay TE, and winding of relay TEP, to The picking up of this relaycloses a stick circuit through front contact 66 for shunting thecontacts 57 and 102, out of the circuit just described. Relay TEP whenpicked up restores the timer TE by opening its circuit at back contact84.

Upon the picking up of relay TEP as has been de scribed, the relay 3WRPbecomes energized through back contact 53 of relay 3WZ and front contact67 of relay TEP, and the picking upof this relay causes the operation ofthe track switch 3W to its reverse position by a mode of operation thathas been described. This conditions the system so that the signal 6B canbe cleared through front contact 79 of relay 3RWP, and the first part ofthe train can be backed into the passing siding B to leavethe cars asrequired. When this train is fully in the rear of signal 73, the relay7H picks up, and the picking up of this relay maintains the relay SWRPin its energized position and thus maintains the track switch 3W reverseso that it is unnecessary to wait for timer operation before thelocomotive initiates another switching move out of the passing siding Bto couple up to the 11 rear end of the train which has been left in thetrack section 6T.

Thus, the operator at the controloffice sends out the proper centralizedtrafiic control for the clearing of signal 73 to move the locomotive outonto the main track, and after'the locomotive has passed through thedetector track section 31', the track switch '3W-isautomaticallyoperated back to its normal position according to a mode ofoperation that'has'been 'heretofore described, but the timer TE isinitiated so that the relay TEPis picked up after operation of the timerTE to operate the track switch 3W to itsreverse position andthus permitpassage of the locomotive through track switch- 3W to couple up with therear endof its train in thetrack section 6T and thus be-in condition toproceed according to'normaloperation for westbound trains through theblock betweenpassingsidings A and B.

Having thus described one embodiment of a safety track switch control'systemas provided by thepresent invention, it is desired to beunderstood that this form has beenused principally .to disclose thegeneral organization and principles of operation rather than to disclosethespecific organization that would be employed in practice, and it isdesired to be understood that various adaptations, alterations,andmodifications may be made to the specific form shown according to therequirements of practice without in any manner departing from thespirittor scope ,ofthe. present invention exceptas limited by theappended claims.

What I claim is:

1. A safety track switch control systemcomprising in combination, astretch of railway track having a safety track switch connected thereto,said stretch of track being divided into a plurality of adjoining tracksections, a particular one of said track sections being of a length tocontain completely only a short train, manually operable means fordesignating respective normal and reverse positions for operation ofsaid track switch, timing means including certain of said track sectionsoperable to indicate the speed of an approaching train as being at orbelow a predetermined medium speed and at or below a predetermined lowspeed, a switch control relay for governing operation of said trackswitch, circuit means operable whenrendered effective to energize saidswitch control relay subsequent to the operation of said manuallyoperable means for designating the reverse position for said'trackswitch, said circuit means being renderedefiective when atrain isapproaching said track switch only provided said timing means indicatesthe train is approaching at or below saidpredetermined low speed as longas .the train continues to occupy simultaneously a plurality of. saidtracksections including said particular tracksection, and said circuitmeans being rendered effective when atrain is approaching said'trackswitch if .said timing means indicates the train is approaching at orbelow saidpredetermined medium speed provided that the train isindicated as being short by being fully contained within said particularone of said track sections, andmeans for operating said track switch torespective reverse and normal positions in accordance with therespective energized and deenergized positions of said-switch controlrelay.

2. A safety track switch control system for railroads comprising incombination, a stretch of'railway track having a safety track connectedthereto by a power operable track switch, said stretch of track havingthree adjoining track sections in approach of said track switch, thelength of the intermediate of the three track sections being justslightly greater than the length of a long passenger train, a switchcontrol relay, means including said switch control relay for operatingsaid track switch, two timing devices having respective short and longtime settings, means for initiating both of said timing devicessimultaneously upon the approach of a train to said track switch, andcircuit means for operating said switch control relay when only saidintermediate track section is occupied provided said timer having ashort setting has completed its operation, saidcircuit means beingeffective to operate said switch control relay when said intermediatetrack section and the preceding adjoining track section but not theother adjoining track section are occupied by a train approaching saidtrack switch provided that said timing device having a long time settinghas completed its operation.

3. A safety track switch control system for railroads comprising incombination, a stretch of railway track having a safety track connectedthereto by a power operable track switch, said stretch of track beingdivided into three adjoining track sections in approach of said trackswitch, a switch control relay, means for operating said track switch inresponse to the operation of said relay, two timing devices havingrespective short and long time settings, means for initiating both ofsaid timing devices simultaneously when a train approaches said trackswitch, and circuit means for operating said switch control relay inaccordance with the completion of operation of either of said timingdevices, said circuit means being effective subsequent to completion ofoperation of said timer having a short time setting provided that onlythe intermediate one of said track sections is occupied by a train, andsaid circuit means being eflective subsequent to completion of operationof said timer having a long time setting provided that said intermediatetrack section and the next preceding track approaching said track switchsection are occupied by a train and the other track section adjoiningsaid intermediate track section is unoccupied.

4. A safety track switch control system for railroads comprising incombination, a stretch of railway track having a safety track connectedthereto by a power track switch, said stretch of railway track havingthree adjoining track sections in approach of the safety track switch,manually operable means for designating the respective normal andreverse positions for operation of said track switch, two timing deviceshaving respective short and long time settings, means for initiatingboth of said timing devices simultaneously when a train approaches saidtrack switch, and circuit means effective subsequent to the actuation ofsaid manually operable means for designating the reverse position forsaid track switch for operating said track switch to its reverseposition only subsequent to completion of operation of said timingdevice having a short time setting provided only the intermediate one ofsaid track sections is occupied by a train or only subsequent tocompletion of operation of said timing device having a long time settingprovided a train is occupying the first two of said track sections inapproaching the track switch but the third of said track sections isunoccupied.

5. A safety switch control system for railroads comprising incombination, a stretch of track including a power operable safetyswitch, said stretch of track being divided into at least threeadjoining track sections in approach of said switch, a track circuitincluding a track relay for each of the track sections, a switch controlrelay for governing the operation of said track switch, two timershaving different times of operation, means for initiating both of saidtimers upon the approach of a train to said track switch as detected byoccupancy of one of said track sections, circuit means for operatingsaid switch control relay to a position for the operation of said trackswitch to its reverse position subsequent to completion of operation ofa selected one of said timers but prior to the dropping away of saidtrack relay for the last of said adjoining track sections to be occupiedin approaching said track switch, and means including contacts ofcertain ones of said track relays for selecting one of said timers togovern said circuit means only provided the approaching train occupiesthe intermediate one of said three track sections but not its adjoiningtrack sections, said circuit means being operable to select 6. A safetyswitch control system for railroads comprising in combination, a stretchof railway track including a power operable safety track switch, saidstretch of track being divided into at least three adjoining tracksections in approach of said track switch, a track circuit including atrack relay for each of the track sections, a switch control relay forgoverning the operation of said track switch, manually operable meansincluding said switch control relay for governing the power operation ofsaid track switch, two timing devices having different time settings,means for initiating said timing devices at substantially the same timeupon the approach of a train to said track switch, and circuit meanseffective to prevent the operation of said track switch to a particularposition in response to the operation of said manually operable meansuntil the timing device having the longest time setting has completedits operation except that said circuit means is effective to permitoperation of said track switch to said particular position when saidtimer having the shorter time setting has completed its operationprovided that the approaching train is occupying an intermediate one ofsaid track sections but not the adjoining track sections.

References Cited in the file of this patent UNITED STATES PATENTS1,763,011 Shaver June 10, 1930 1,827,829 Thompson Oct. 30, 19311,913,729 Shaver June 13, 1933 2,061,756 Crago Nov. 24, 1936 2,208,436Synder July 16, 1940 2,307,476 Vanhorn J an. 5, 1943 2,385,179 AllenSept. 18, 1945 2,651,711 Iohanek et a1. Sept. 8, 1953 U. S. DEPARTMENTOF COMMERCE PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 2,817,013December 17, 1957 Robert F. Wells It is hereby certified that errorappears in the printed specification of the above numbered patentrequiring correction and that the said Let ters Patent should read ascorrected below.

9 and 30, strike out ("approaching said track switch! Column 12, lines 2ix-aim" in line 31, same column,

and insert the same after Signed and sealed this 25th day of March 1958.

(SEAL) Attest:

KARL Ho AXLINE Attesting Officer Comnissioner of Patents

